Si ON THE CULTURE 



fary to bring it to and keep it in a proper degree m 

 heat ; and as foon as the heat rifes in the linings, it 

 circulates in the flues, and warms every part of the 

 •bed ; whereas the dung for making a common cu- 

 cumber bed mull be turned and worked, and lie, 

 till, by fermentation, its rank qualities be evaporat- 

 ed, and its violent heat be fomewhat diminiflied. 



In the courfe of the winter a dung bed finks fo low 

 that it becomes difficult fometimes to get a proper 

 heat raifed in the linings ; but my brick bed being 

 always of the fame height, fuch difficulty can never 

 happen. 



The linings of my brick bed retain the heat longer 

 than the Unings of a dung bed do, and that becaufe 

 • the flues are confliantly full of fl:eam ; but a dung bed 

 : having little or no vacuity for the retention of the 

 lieam, the fleam of the linings of it is more imme^ 

 diately evaporated, and confequently the heat of the 

 liniDgs is fooner exhaufl:ed than the heat of tlie linings 

 of the brick bed. 



To illufi:rate this a little farther, it may be obferv- 



ed that there is a certain quality in dung which is the 



. caufe of its heating. While this quality, or any part 



■ of it, remains in the dung, it retains the heat in fome 



degree ; but when that quality is totally exhaufl:ed, 



the heat in the dung ceafes. 



^ There is another method befides that of fermenta- 

 tion by which dung may be deprived of this qua- 

 Hty ; and that is, by being expofed for fome time 

 to the fun and air in fpreading it thinly on the ground* 

 In that ftate the dung's heating quality will be eva- 

 porated. 



